Anesthesia systems are used to supply patients with breathing gas and volatile anesthetics. Respiration systems in which the breathing gas is circulated in a closed cycle and is again returned to the patient after removal of the expired carbon dioxide are usually used in anesthesia. Only the breathing gas consumed is replaced here.
Due to the circulation of the breathing gas in the closed breathing system, the breathing gas becomes enriched with moisture and water of condensation may be formed. So-called water traps, preferably in breathing tubes, are used to collect water of condensation, and these water traps must be checked and emptied at regular intervals. Disposal of water of condensation is not normally possible and would make handling of the anesthesia system difficult during the use of the device, which may sometimes continue over several days.
A disposable filter for cleaning expired gas is known from US 2003/0 167 927 A1. The filter is located in a filter housing, and the filter housing has a gas inlet and a gas outlet. A collection volume for water of condensation is located at the deepest point of the filter housing. The collection volume consists of transparent material and a color indicator is used to make it easier to monitor the filling level of the water of condensation in the collection container.
The drawback of the prior-art device is that water of condensation may flow back when the position of the inserted filter is changed when the collection volume is filled and water of condensation collects on the underside of the filter element.